Five-Membered Rings Create Off-Zero Modes in Nanographene

• DOI: 10.1021/acsnano.3c06006
• Publication Date: 2023-12-05T18:45:54Z
• Authors: Peter H. Jacobse; Michael C. Daugherty; Kristia̅ns Čerņevičs; Ziyi Wang; Ryan D. McCurdy; Oleg V. Yazyev; Felix R. Fischer; Michael F. Crommie
• Keywords: Zero-point energy; Zero mode; Zigzag

The low-energy electronic structure of nanographenes can be tuned through zero-energy π-electron states, typically referred to as zero-modes. Customizable and magnetic structures have been engineered by coupling zero-modes exchange hybridization interactions. Manipulation the energy such however, has not yet received significant attention. We find that attaching a five-membered ring zigzag edge hosting zero-mode perturbs mode turns it into an off-zero mode: localized state with distinctive electron-accepting character. Whereas end states typical 7-atom-wide armchair graphene nanoribbons (7-AGNRs) lose their electrons when physisorbed on Au(111) (due its high work function), converting them modes introducing cyclopentadienyl rings allows retain single-electron occupation. This approach enables properties 7-AGNR explored using scanning tunneling microscopy (STM) gold substrate. gradual decrease between function GNR length, evolution from more closed-shell open-shell ground state.